Television and sound multiplex system



P 1950 J. H. HOMRIGHOUS 2,521,008

TELEVISION AND SOUND MULTIPLEX SYSTEM Filed June 27, 1944 4 Sheets-Sheet 1 MIKE AME 8 25 :3 1 6 7 M00. POWER AMP AME T r--? ls osc -33 ,2 Fl 6 I 1 .21/

25 FIG 2 INVENTOR.

OI ICC 139 101 Sept. 5, 1950 J. H. HOMRIGHOUS 2,521,008

TELEVISION AND SOUND MULTIPLEX SYSTEM Filed June 27, 1944 4 Sheets-Sheet 2 Sept. 5, 1950 .1. H. HOMRIGHOUS 2,521,003

TELEVISION AND SOUND MULTIPLEX SYSTEM Filed June 27, 1944 4 Sheets-Sheet 3 I60 I50 I40 I53 U- '4' POWER R F AMP.

AMF. A\

\ POWER '59 I43 |44 I45 I48 I49 IST. V|D5 2ED MESS- POWER SOUND DET. LE DET. f" DISI AMP I I47 HOR. v osc. DEF. D EF me APP FIGS I72 I67 I7? FIG 7 ms INVENTOR.

Sept. 5, 1950 J. H. HOMRIGHOUS 2,521,008

TELEVISION AND SOUND MULTIPLEX SYSTEM Filed June 27, 1944 v 1 4 Sheets-Sheet 4 AUTO.

DEE

Patented Sept. 5, 1950 TELEVISION AND SOUND MULTIPLEX SYSTEM John H. Homrighous, Qal Parlz, Ill. icatio J me 1944. serial NP- 2 31 12 Claims. (01. ire-5,5)

This invention relates'to radio communication systems and more particularly to. a television system for the transmission and reception of pietures and the accompanying sound.

One of the objects of my invention is to provide an improved System for controlling the scanning actions in cathode ray'tubes both horizontally and vertically by control signal pulses having relative short periods of time, and signal pulses of the same amplitude, but having relative long periods of time.

Another object of my invention is to provide automatic deflection control or automatic pica tore size control, here the size of the reproducedpicture is automatically maintained at a predetermined width and height.

Another object of my invention is to provide an improved method or system for the transmission and reception of sound signals on the same carrier with the picture signals.

Another object is to provide means for developing groups of control or line pulses separated by single pulses of longer duration for picture field control.

Another object is to provide an improved sys-v tern for separating line and field control pulses having the same amplitude.

Another object is to provide means for trans mitting time of day and weather reports simultaneously with the'pictures.

Another object is to provide an improved method and system for controllingtelevision re,- ceivers from conventional synchronizing signals.

Another object of my invention is' an improved means for developing control signals of ong 311d short duration during the interval between scanned lines in a field and between the pieture fields for controlling the scanning action at the transmitter and to modulate the carrier with h e lo d c trol S nals; ring the int r al between scanned lines and picture fields to thereby govern the scanningact o s at the re iv n station. i

Another object is to provide an improved means for controlling interlace scanning;

An h ob of m inve ti i to crevice m d modu a in con o s o t ansm t ie video si n s nd sound signa s i m two dif e ent messages on the same carrier.

Messages in this specification are to he under;- stood to include any intelligence represented by sound, or picture signals.

fir s anni control sy t m le ibed thi spe ifiqati n mare 'p ov ont l i n o 'edua amplitude and is somewhat similar to my Selfsynchronizin Systems shown and described in co ndingapplications Serial Number" 451,722, ury 21,1942 now Patent No. 2,398,641, ed'Ap'ril '15,, 1946, and Serial Number 476,897, sled F b ary 24, 19,43ym that the line control p es; may return the cathode ray from any locatlon on its associated screen, in the receiver station to the starting'point for the next horizontal line, andthe f eld control pulse may return the cathode ray'froni any location on its associated screen in the receiver to the starting point for the first horizontal line in another frame or picture. This, control systen'imay be known also as the fol 'u system, that is, the receiving station is not drivenintosynchronismbut follows the hori zlontal and vertical movements of the transmitting station. is every versatile control system since a. receiver m'ayrespond to any number of lines per picture and also to a wide range i qi ti r' fram h se n other bjec 's an advanta es. o my nve n will appear from the following description taken in connection with the accompanying drawings, inwhich:

' li'i'g es 1 and 6 are simplified diagrammatic views of; a television transmitting station and a television receiving Station respectively; illustrating the principles applied in this invention.

Fi ure s. r i di' ram howin the me sage" distributor illustrated in Figure 1.

"Figure 3 is a'circuit diagram showing the hori- Zontal and ve c l d flecting appa atus l usated in F u Figure 4 is a graphical view illustrating the time" intervals for the various messages includi' "g the control signals. s re 5 s. a. graph cal view us rati hor zontaland vertical control pulses.

Figure 7 is a circuit diagram sh wing the message distributor illustrated in Figure 6. "Figure 8 is a circuit diagram showing the 1101i. zohtalfand vertical deflecting apparatus ilius trat' inIEig ure 6.

Figure 9 is a graphical view of a saw tooth v v Figure 10. is a graphical v w illustrating conventionalf horizontal and vertical control pulses. With'reierence to Figure 1 the numeral pl desighates a cathode ray transmitting tube of'conve t a1 type, and, asillustrated it comprises ie 2,. a ph to e ec r sc n o wh h a ight im se' ithe obje i pro e ted nd n electrongun f or generating a ray of electrons dire edtoward' the scrcenfand' two sets of. 1 fleeting plates'for deflecting the electron ray at 3 the line and field frequencies, so that it is caused to scan the screen. The picture signals are thereby developed and fed to a video frequency amplifier 3; from the amplifier 3 the video or picture signals are fed to the message distributor The message distributor 4 allots suitable pe-' riods of time during each horizontal saw tooth wave developed in the horizontal deflecting apparatus I2 for the picture signals and fragments of sound signals from two different messages which are fed to the modulating amplifier I3 together with the horizontal control signals from the deflecting apparatus I2 and the vertical control signals from the vertical deflecting apparatus I l. The picture signals and sound signals for .both messages occurring between the line control signals, and the frame control signals occurring between groups of line signals for the lines in picture fields or frames.

A carrier wave is provided by the oscillator I5. In the power amplifier I6 this carrier wave is modulated by the picture signals, sound signals, and control signals, which are applied by a connection Il' to the antenna I8.

Sound signals from two different messages, picture signals, and control signals may be transmitted 'on the same carrier where the rate of change from one message to another message is considerably greater than the frequency of electrical signals produced by sound.

With reference to Figure 2 the message distributor 4 for alloting suitable periods of time in a saw tooth wave for several messages comprises multi-element gate amplifier tubes I9, 20, and 2| having their anodes connected together and coupled through condenser 22 to the grid of the modulating amplifier I3. Video amplifier 3 output is connected in the cathode grid circuit of'amplifier I9, sound amplifier 6 is connected to the cathode grid circuit of amplifier 20 and the output from sound amplifier II is connected to the cathode grid input circuit of amplifier-2|. Off and on relay or impulse tubes 23 and 24 and other like tubes throughout this specification conductors 25 and 25 to the control electrodes 2'I' and 28 respectively. As each saw tooth wave is developed for deflecting the electron ray forward over its associated screen, to be explained later, the gradually increasing potential is applied to the control electrode 21 and 28 which may be adjusted in the circuits of Figure 3 so that the potential on control electrode 21 may permit the I electrons from the cathode 29 tofiow to the anode 39 at the time the electron ray in the cathode ray tube I reaches the leaving edge of the image screen 2 so that the picture signals developed on 4 v the forward horizontal movement of the'electron ray are fed to the input circuit of the amplifier tube I9, the output of tube I9 being applied to the control grid of modulation amplifier I3. Current flowing through the anode 30, cathode 29, circuit of tube 23 causes a potential drop at the load resistor 3I which is applied to the grid 32 of tube 19 to block any signalling current in this tube during further increases in the saw tooth potential. This drop in potential at resistor 3| is also applied over conductor 33 to the control electrode in the cathode ray tube I Figure 3 to substantially extinguish the electron ray during further increases in the saw tooth potentials.

The potential drop at the load resistor 3| is applied to the control electrode 34 which may rotate or block the electrons from the anode 35, thereby increasing the potential at load resistor 36 and on the grid 3? in tube 2!; thus permitting sound signals from the amplifier 6 to be supplied to the control grid of the modulation amplifier I3 immediately after the picture signals were modulated. However, after a short period of time for modulating the sound signals from amplifier 6 the sawtooth potential on the control electrode 28 in tube 24 will have increased to permit electrons to how from the cathode 31 to the anode 38, thus producing a potential drop at the load resistor 39 which is applied to the grid 40 in tube 26 to block the cathode anode signalling current through the tube 2B. The potential drop at resistor 39 is also applied to control electrode 4|, which drives the electrons from anode 42, thus increasing the potential at the load resistor 43, and to the grid 44 in tube 2|. The increase potential on grid 44 renders tube 2| conductive to sound signals from the reproduction amplifier II immediately after the sound signals from amplifier 6 have been blocked. After the tube 2| has become conductive for a short period of time control signals are developed in the circuits of Figure 3 to. trigger the saw tooth voltages and to restore the circuits of Figure 2 to start another group of signals comprising picture signals, and sound signals from two different messages through the amplifiers 3, 6 and II respectively.

Referring to Figure 4 the difierent periods of time for the several difierent signalsmay be as illustrated wherein 2 may represent the mosaic screen and the line 45 the period of time for picture signals, 46 may represent the period of time for sound signals associated with the picture signals, 41 sound signals from a different message, such as time of day and weather reports, and 48 may represent the period of time for horizontal control signals. It is to be understood that the period of time for; any of the several signals may be varied to suit conditions.

From the above description it is seen that picture signals and signals from two different sources of sound together with control signals may be modulated in successive rotation on a single carrier. The horizontal line deflection may be at fifteen thousand per second or higher which causes the sound signals to be interrupted at the same rate. The rate of interruption being relatively highand near the upper range of audibility they will not cause objectionable interference in the sound reproduction.

With reference to Figure 3, the apparatus and associated circuits I2 for producing horizontal sweep voltages comprise a condenser 49 charged through an adjustable resistor 50 from a source of positive potential as, indicated. By movement of the switches EI and 52, another condenser 53 may be charged through resistor 54 from a source of positive potential to vary the line frequency for horizontal deflection. Other line frequency variations may be obtained by providing other resistors and condensers connected to the vacant switch contacts.

When the condenser 49 or 53 becomes charged, depending upon which switch contacts are closed, the saw-tooth voltage wave in the plate circuit of tube 55 is impressed on the grid 56 of multiunit tube 51 through an adjustable contact on resistor 58 for controlling or adjusting the amplitude of the saw-tooth voltage wave. The double anode output of the amplifier 51 supplied to the load resistors 59, 60, 6|, 62, 63. and 64 will change the potential on the horizontal deflecting plates 64 and 65 of tube I to effect in a well known manner the horizontal movement of the electron ray.

To initiate the discharge of condensers 49 or 53, I provide an off and on relay tube 66 having its control electrode 61 connected to the load resistor 62 through an adjustable contact 65. As the saw-tooth voltage increases to a suitable amplitude to cover the time periods for picture and sound signals the electrode 61 becomes more positive thus permitting electrons to flow from the cathode 68 to the anode 69, causing a voltage drop at load resistor 10 which is applied to the control grid of tube H, thereby increasing the potential at load resistor I2 to produce a positive pulse which may be applied to the grid 13 of the trigger tube 55 rendering this tube conductive to discharge the condenser 49 or 53, thus returning the cathode ray to start scanning the next horizontal line. The discharge of the condenser 49 produces a potential drop in the load resistor 62 which is applied to control electrode 61 to drive or rotate the electrons from the anode 69. Likewise the potential drop in load resistor 63 and 64, supplied over conductors 26 and '25 to the control electrodes 28 and 21 in tubes 24 and 23, restores the circuits of the message distributor 4 to the proper condition to again start modulating picture signals.

The positive pulse developed in tube 1| may be supplied over conductor I4 to the grid of modulation amplifier I3 to modulate thecarrier with a pulse during horizontal retrace or as the condenser 49 is being discharged. to control the scanning action at the receivers. The voltage drop at resistor 10 may also be applied to the control grid of the cathode ray tube I to substantially extinguish the ray during retrace.

From the foregoing it. will be understood that the tube 66 initiates the control impulse for the line return trace of the cathode ray, and causes the carrier to be modulated with a high amplitude signal after the termination of each group of signals comprising picture signals and fragments of sound signals from two different sources. Furthermore, line frequency may be varied to meet any operating condition through the condensers 49 and 53 and the adjustment of. the resistances and 54.

The apparatus. and associated circuits I4 for producing vertical sweep voltages are similar to the apparatus and circuits used for horizontal sweep Voltages and comprise a condenser 15, charged through an adjustable resistance 16 fromv a source of positive potential as indicated. By movement of the switches 11 and 18 another condenser 19 may be charged through resistance 80 from a source of positive potential to vary the frame frequency.

When the condensers 15 or I9 become charged, depending upon which switch contacts are closed, the saw-tooth voltage wave in the plate circuit of tube 8| is impressed on the grid 82 of multiunit tube 83 through an adjustable contact 84 for adjusting the amplitude of the saw-tooth wave. The double anode output of the amplifier 83 supplied to the load resistors 85, 86, 81 and 88 will change the potential on the vertical deflecting plates 89 and 90 of tube I to efiect the vertical forward movement of the electron ray.

To initiate the discharge of condenser 15 or 19, I provide an elf and on impulse tube 9| having its control electrode 62 connected to the load resistor 88 through an adjustable contact 93. As the vertical saw-tooth voltage increases to a suitable amplitude to cause the cathode ray to travel vertically over the screen, the electrode 92 becomes more positive thus permitting electrons to flow from the cathode 94 to the anode 95 causing a voltage drop at load resistor 96 which is applied to the control grid 61 of tube 98 thereby causing a positive pulse to be supplied over conductor as to the grid of modu-- lation amplifier I3, to modulate the carrier be-- tween picture frames with a vertical control. signal. may be for a longer time interval than the horizontal control pulses as illustrated in Figure 5 where we may represent a vertical control pulse and it'll may represent horizontal control pulses. having equal amplitude. In order to produce a pulse having a relatively long period of substantially constant amplitude, the increases in potential at load resistor I02 may also be applied to the grid I83 of tube I04 to cause anode cathode current to flow through the adjustable resistance N15 to charge the condenser I66. As the condenser I06 becomes charged the potential in the plate circuit of trigger tube IN is impressed on the control electrode I68 of ofi and on impulse tube I09. After a suitable length of time depending on the value of resistance I05 and condenser I06 the electrons may flow from the cathode I I 0 to the anode i II causing a voltage drop at resistance I I2 which is applied to the control grid of tube H3 initiating a positive pulse to trigger tubes 8| and I0! discharging the condensers 15 and I06 to return the cathode ray to start the first line in the next field. The positive pulse over conductor 99 may also be applied .over the connecting conductor 4 to the grid of horizontal trigger tube 55 to return the cathode ray horizontally each time the ray is returned vertically.

From the above description it is seen that a vertical control pulse may be produced at the end or each held to initiate both the vertical and horizontal retrace, extinguish the cathode ray during retrace and modulate the carrier with a relatively wide control pulse between pictures. Furthermore, line and frame frequency may be varied tomeet any operating condition.

Itis to be understood that picture signals and the control signals may be transmitted on the same carrier and the accompanying sound signals may be transmitted on another carrier in which case the cathode ray return or retrace would be initiated at the leaving edge of the mosaic.

To provide interlace scanning where the linesof one fieldv fall in between the lines of the previous, field, I providemeans for initiating the backward horizontal deflection. .of the ray from substantially the mid-point of the screen The vertical control signal or pulse.

for the first horizontal line in alternate fields. In order to trigger tube 55 at the-mid-point of a line, the increase of potential at the load resistor I02 occurring at the end of each scanned field is applied to the grid II5 to cause anode cathode current to flow for a short period of time through the adjustable resistor II6 to charge the condenser In. As the condenser II'I receives a charge at the end of each forward vertical trace the potential in the first plate circuit of tube H3 is impressed on the control electrode I I9 of the impulse tube I20. The values of the resistor H6 and condenser II! are chosen so that at the end of alternate field periods or for each two momentary charges of current through the resistor II6 the control electrode a II 9 will become sufilciently positive to permit current to flow through the tube I20. The voltage drop at load resistor I2I may be applied to the grid of tube I22 increasing the potential at load resistors I23 which may be applied to the grid I24 in tube I25. The increased potential on grid I 24 may permit current to flow from the plate I26 to the cathode I21 when the potential on control grid I28 is increased. The control electrode I29 in the impulse tube I36 may be connected to the load resistor 59 and adjusted so that as the horizontal saw-tooth potential is increasing the control electrode I29 will become sufficiently positive when the cathode ray has reached substantially the mid-point of the screen or further along when sound is modulated on the same carrier, to permit current to flow from the anode I3I to the cathode I32 causing a voltage drop at resistor I33 which is applied to control grid I34; after suitable amplification the impulse is fed to the control grid I28 and if the grid I24 is sufficiently positive to permit current to flow which is the condition in alternate fields as explained above, causing a voltage drop at load resistor I35 which is applied to the control grid I36 in tube IIB. The'voltage drop on grid I36 causes a high potential pulse on the anode I3? which is applied to the grid E3 of trigger tube 55 discharging the condenser 49 to return the cathode ray to start the'second line. This same pulse may be applied to conductorlfi to modulate the carrier. The pulse on the anode I31 may also be applied to the grid I 36 of tube II8 causing the condenser II! to be discharged through the first anode circuit of tube II8.

From the above description it is shown that the cathode ray will be returned or deflected backward from substantially the mid-point of the screen in the first line in alternate fields which will place the lines in one field in between the lines of the previous field; also the carrier will be modulated with a control signal as illustrated at I39 Figure 5 in alternate fields to control the horizontal backward deflection of the cathode ray in the receiver from the mid-point of the screen, to be further explained later.

From the description it is shown that horizontal control pulses are produced in groups separated by vertical control pulses of longer duration for controlling the scanning actions at the transmitter, and that these pulses are modulated on a carrier for controlling similar scanning actions at receiver stations.

With reference to Figure 6, showing a receiving station, the antenna I40 receives the carrier signals from the transmitter antenna I8 to a radio frequency amplifier I4I. An oscillator I42 reacts with these signals in the first detector stage I43 on the heterodyne principle to produce an intermediate frequency which is supplied to the video and sound intermediate frequency stage I44. After suitable amplification the video signals, sound signals and control signals are demodulated at I45. The control signals being of greater amplitude are separated and fed to the horizontal and vertical defiectingapparatus and associated circuits I46 and I4! to control the scanning actions in the viewing tube I48. The video signals and sound signals from'two different sources are fed from the second detector I45 to the message distributor I48 where the several signals are separated and allotted suitable periods of time and then fed to individual poweriamplifiers I49, I50-and I5I. The picture signals being supplied to the power amplifier I49, the sound signals accompanying the pictures being supplied to the power amplifier I50 and the sound signals for time of day and weather reports being supplied to the power amplifier I5I. A key I52 is-provided for switching the loud speaker I53 from the reproduction of sound signals accompanying the pictures at the amplifier I50 to the reproduction of signals from amplifier I5I. The video or picture signals are fed from the amplifier M9 to the viewing tube I48; The viewing tube I48 is represented as being in the form of a cathode ray tube of a conventional type and comprises a fluorescence screen I54, an electron gun for developing a ray of electrons directed toward the screen and two sets of electrostatic plates for deflecting the electron ray at the line and field frequencies to cause it to scan the screen. The video signals are applied to the control electrode of the electron gun, whereby, the intensity of the electron ray is made to vary with the video or picturesignals. The'horizontal saw-tooth voltages are fed over conductor I55 to the message distributor I48 for controlling the several time periods.

With reference to Figure 7, the message distributor I48 for alloting suitable periods of time in the interval of a saw-tooth wave for several received messages comprises two oil and on impulse tubes I56 and I5! for controlling the power amplifiers I49, I59 and IEI, and a multiunit tube I58 for separating control signals from the picture and sound signals. The tubes I56 and I5! are controlled by saw-tooth voltages developed in the apparatus and associated circuits of Figure 8 and applied over conductors I59 and I60 to the control electrodes l6l-and IEZ-respectively. As each sawtooth wave is developedfor deflecting the electron ray forward over its associated screen, to be explained later, the gradually increasing potential is applied to the control electrodes I6I and I62 which may be adjustedin the circuits of Figure 8 so that the potential on the control electrode I6I may permit the electrons from the cathode I63 to flow to the anode I64 at the time the electron ray in the cathode ray tube I48 reaches the leaving edge of the screen I54, so that received picture signals from the detector I45 may be supplied to the control grid of the power or gate amplifier I49, and after suitableamplification in this tube they are applied over conductor I65 to the control grid of the viewing tube I48 where they are reproduced on thelorward horizontal movement of the ray. As soon as current flows from the anode I64 to the cathode I63 a voltage drop is developed at the load resistor I66 which is applied to the grid I 61 to render tube I49 inoperative to any further signals applied to its control grid during further increases in the saw-tooth potential or during the time that sound signals and.

control signals are being received. The drop in potential at resistor I69 is also applied over conductor I68 to the control grid of picture tube I48 to substantially extinguish the electron ray during reception of sound signals and control signals or during further increases in the saw-tooth voltage developed in the circuits of Figure 8.

The potential drop at the resistor I88 is applied to the control electrode I89 which may rotate or block the electrons from. the anode I10, thereby increasing the potential at load resistor HI and to the grid I12 in the gate amplifier tube I50, thus permitting received sound signals applied to the control grid I13 to be amplified in tube I50, and supplied to the loud speaker I53 through the key I52 immediately after the reproduction of the picture signals. A short period of time after the reception of sound signals the saw-tooth voltage on control electrode I92 will have increased to permit current to fiow from the anode I14 to the cathode I15 thus producing a potential drop at the load resistor I16 which is applied to the grid I11 in tube I50 thus blocking this tube to any sig nals on the control grid during further increases in saw-tooth potentials. The drop in potential at resistor I16 is also applied to the control grid I18 rotating or blocking current fiow from the anode I19, thereby increasing the potential at resistor I80 and grid I8I. As soon as the potential on grid I8I is increased the gate amplifier tube II becomes sensitive to received sound signals from a second message, such as time of day or weather reports, which may be reproduced at any time by pressing key I52 to connect the loud speaker to the output of tube I5I. After tube I5I has become conductive to sound signals for a short period of time the tube I 5! becomes blocked by negative potential on the grid I82 controlled by received signals or impulses as will be presently explained.

Control signals demodulated at I45, after the sound signals from fragments of a second message have been demodulated, are blocked from effecting the power amplifiers I49 and I59 as explained above. However, received horizontal and vertical control impulses of relatively high amplitude as illustrated in Figure 5 may be applied to the grid I83 of tube I58, the grid being biased to prevent picture or sound signals from effecting the output. The control impulses applied to grid I89 cause a voltage drop at resistance I94 which is applied to grid I82 of tube I5I to block this tube during the retrace period. The pulses in the first anode circuit of tub I58 are applied to grid #05 and after suitable amplification in the second anode cathode circuit of this tube the pulses are fed over conductor I95 to the circuits of Figure 8 to control the saw-tooth voltages and. restore the circuits of Figure '1 to start reception of another series of signals comprising picture signals and sound signals from two different messages.

With reference to Figure 8 the apparatus and associated circuits I96 for deflecting the cathode ray horizontally and for producing the saw-tooth potentials to control the circuit of Figure 7 comprise a condenser I81 charged through an adjustable resistor I89 from a source of positive potential as indicated, another condenser I89 and resistor I90 may be employed to change the charging rate.

When the condenser I81 becomes charged, the saw-tooth voltage wave in the plate circuit of tube i2! is impressed on the grid I92 of multi unit tube I93 through an adjustable contact on resistor I94 for controlling the amplitude of the saw-tooth voltage wave. The double anode output of th amplifier I93 supplied to the load resistors I95, I98, I91, I98 and I99 will change the potential on the horizontal deflecting plates 200 and 20I of tube I48 to effect in a well known I denser I91 to return the electron ray from any tube I93.

point reached on the screen to start the next line, therefore, the horizontal scanning action may be synchronized with the transmitter upon the reception of the first horizontal control signal.

To initiate the discharge of condenser I81 in the absence of control'signals due to fading or when tuning the set, I provide an oil" and on impulse tube 292 having its control electrode 203 connected to the load resistor I99. As the sawtooth voltage increases to a suitabl amplitude, to cover the predetermined time periods for picture and sound signals the electrode 293 becomes sufliciently positive to permit current to flow through the load resistor 204, causing a voltage drop to be applied to the control electrode 205 blocking the current flow through load resistor 296, thereby producing an impulse which may be applied to the control grid of trigger tube I 9|.

In order to provide automatic deflection control or automatic picture size I employ a slowacting tube 201 for controlling the current flow in tube I93. The slow-acting tube is described in my co-pending application Serial No. 541,941, filed June 24, 1944, now Patent No. 2,425,877, issued August 19, 1947. Briefly this tube comprises a triode having an anode 208 of mesh material covered with luminescent material of rather slow decay. As the electrons strike the plate it may glow with a brillancy determined by the grid potential. The member 209 is a shield at cathode potential to direct the electrons toward the plate. Adjacent to the anode is a photo electric device comprising an anode 2I0 and cathode 2II adapted to be actuated by the brilliancy of the triode plate.

The control grid 2I2 in tube 201 is connected in parallel to the control grid I92 in tube I93.

As the saw-tooth potential increases more electrons will flow from the cathode to the plate 208, thereby increasing its brillancy which is reflected to the cathode 2II causing an increase in current from positive potential at anode 2I0 to cathode 2II through resistor 2I3, which may be applied to the grid 2I4 in the tube 2I5. The anode output of amplifier 2I5 supplied to the load resistor 2I9 causes a potential change on the grid 2!! to control the current flow through In other words, as the plate 208 increases in brilliancy the grid 2E1 becomes more negative to reduce the current through tube I83. The operation is as follows: the saw-tooth wave produced by charging and discharging a condenser is adjusted so that the desired amplitude is reached a short period of time before the control pulse is received to discharge the condenser, or the saw-tooth potential developed on the grid 2I2 is greater than required which will 11. cause the .plate 208 to obtain a certain value, which may be adjusted at the voltage divider 2| 3 to regulate the potential on the grid 2H, thereby adjusting the current flow in the tube I93, which changes the potential on the load resistors N35 to I99 inclusive. Since the luminescence or phosphorescence material on the anode 208 is of relatively slow decay it will maintain the current through its associated photo electric device,

substantially constant during recurring sawtooth waves.

Figure 9 illustrates two saw-tooth waves, one with high amplitude and the other with lower or adjusted amplitude. The solid line 2 I 9 represents the increasing potential of a saw-tooth wave developed in the triode of tube 2!]? which is triggered at 220 by the impulse represented at 22l. The horizontal line 222 represents the required amplitude and the dashed line 223 may represent the adjusted potential of the sawtooth wave developed in the output of tube I93.

From the above description it has been shown that-the amplitude of saw-tooth waves may be automatically adjusted or maintained substantially constant, which means that the picture size in television maybe automatically adjusted and maintained at the desired screen size. 7

The apparatus and associated circuits I41 for producing vertical sweep voltages comprise a condenser 224 charged through an adjustable resistor 225 from a source of positive potential as indicated. By -movement of theswitches 225 and 22! another condenser 228 may be charged through resistor 229 from a source of positive potential to vary the frame or field frequency of trigger tube l9! and also to the grids of the double unit tube 24!]. The vertical control signals or impulses will trigger the tube l9l to discharge the condenser l8! thus deflecting the cathode ray backward horizontally each time a vertical control signal is received. The control signals both horizontal and vertical impressed on the grids of tube 240 cause current to flow from the anode 2M to the cathode to charge the condenser 242 through the adjustable resistor 243. The increasing potential on the plate of tube 244 is applied through the adjustable resistor 245, switches 246 and 241 to the control electrode 248 in impulse tube 249. Pulses of short duration or horizontal control pulses will not increase the potential on the electrode 248 sufficiently to permit current to flow from the anode 250. However, a pulse of relatively long duration or a vertical control signal causes the condenser 242 to be charged over a longer period of time, thereby increasing the potential on electrode 248 to permit the electrons to flow to the plate 250 causing a voltage drop at load resistor 25!, which is applied to the control electrode 252 blocking the current from the anode 253 to increase the potential at resistor 254; which is applied to the grid of trigger tube 233, causing this tube to become conductive discharging the condenser 224, and causing the vertical backward deflection'of the electron ray.

The control signals impressed on the grids of tube 240 charge and discharge the condenser 242. As the control impulse is initiated on the grid 255 current flow through the anode 255 is increased causing a voltage drop to be applied to the grid of trigger tube 244, but as the grid 255 is re-- stored to normal or becomes less positive, the voltage on the grid of tube 244 becomes more positive causing this tube to become conductive discharging the condenser 242.

From the above it is seen that the condenser 222 will be charged and discharged for each received control signal both horizontal and vertical. But only the vertical control pulses of relatively long duration cause the discharge of condenser 224 to deflect the electron ray backward vertically.

To initiate the discharge of condenser 224 in the absence of vertical control signals due to fading or when tuning the set, ,I provide an off and on impulse tube 251 having its control electrode 258 connected to the load resistor 231. As the saw-tooth voltage increases to a suitable amplitude to cause the electron ray to be deflected over the desired screen height, the electrode 258 becomes sufiiciently positive to permit current to flow through the load resistor 259 causing a voltage drop to be applied to the electrode 269 blocking the current flow through resistor 26!, thereby producing an impulse which may be applied to the control grid of trigger tube 230.

Automatic deflecting control or automatic picture size, illustrated by the block diagram 252,

may be obtained for vertical deflection by similar apparatus and associated circuits used in controlling the horizontal deflection which is also represented by the numeral 252. This equipment 262 varies the potential on grid 263 to control the current flow through the tube 233 as explained for the horizontal deflection further explanation is thought to be unnecessary.

From the above description it is seen that horizontal and vertical scanning actions may be controlled by pulses of equal amplitude but of unequal duration, also that the vertical control signals cause both the vertical and horizontal backward retrace, so that upon reception of a vertical control signal the electron ray is deflected backward both vertically and horizontally from any point it has reached on the screen to immediately synchronize the receiver with the transmitter. Furthermore since the horizontal control signals produced at the transmitter include a pulse to cause the electron ray to be deflected backwards from the midpoint of the screen for the first line in alternate fields. The electron ray in the reeciving tube will likewise be deflected backwards upon reaching substantially the mid-point of the screen in alternate fields to eiTect interlace scanning.

It is to be understood that picture signals only may be transmitted, in which case the sweep potentials may only be of such value as to cause the deflection of the electron ray across its associated screen.

In order to control television receivers from present day conventional control signals comprising a series of vertical signals of relatively long duration between groups of horizontal signals as illustrated in Figure 10 without using the usual arrangement of integrating and differentiating circuits, I employ an improved system whereby the horizontal backward deflection is started immediately upon the reception of a horizontal control signal and both the vertical and horizontal backward deflection is initiated upon the reception of the vertical control signals.

The conventional horizontal signals received would control the deflecting apparatus M6 and associated circuits in the manner as previously described to control the horizontal scanning actions and needs no further explanation.

With further reference to the vertical deflecting apparatus I4! and the associated circuits. Switches 246 and 241 may be operated to include the tubes 264, 265, and 265 in with the equipment of I41. Tubes 240 and 244 will function upon the reception of control signals as above described. The increased potential produced by charging condenser 2 52 is supplied through switch 246 to the control electrode 26! causing current to flow from the anode 258 to the cathode producing a voltage drop in resistor 269, which is applied to the grid 21!! of tube 265 causing a positive pulse to be applied to the grid 21!. Current may now flow upon reception of each vertical control signal from the anode 212 through the adjustable resistor 213 to charge the condenser 2T4. Horizontal control signals will not produce sufficient charge in potential on electrode 251 to permit anode cathode current to flow.

The condenser 2% charged momentarily during each vertical control or synchronizing signal will increase the plate potential in tube 266 which is applied through the adjustable contact 215 on load resistor 7216, switch M! to the control electrode 2 :8. The contact 2'15 may be adjusted so that momentary charges from 6 or more successive impulses may be impressed on the electrode 248 before current starts to flow from the anode 256 to the cathode. The tube 249 will now function as described above to supply a positive pulse to the trigger tube 238 and to the trigger tube 266 to cause vertical and horizontal backward deflection of the cathode ray, and to condition the associated circuits for the reception of the next series of picture signals or picture signals and sound signals.

From the above it is seen that the scanning actions in the receiver may be controlled by horizontal and vertical signals comprising one vertical impulse between groups of horizontal signals or several successive vertical. signals between groups of horizontal signals, and furthermore the oathode ray may be returned both vertically and horizontally from any location it has reached on its associated screen upon the reception of one or more vertical control signals.

In the various circuits shown and described I have simplified the drawings by indicating the source of otential by a sign. Also I have omitted the heater filaments for the various tubes, but it will be understood that such filaments are necessary. 1

The embodiments of the invention which have been given herein are illustrations of how the various features may be accomplished and the principles involved. It is to be understood that the invention contained herein is capable of embodiment in many other forms and adaptations, without departing from the spirit of the invention and the scope of the appended claims.

Having thus described my invention, I claim:

1. In a television system, a cathode ray tube having a screen and an electron ray directed toward the screen, first generator means to produce line saw tooth waves including line pulses to control the intervals of the line saw tooth waves, second generator means to produce frame saw tooth waves including frame pulses to control the intervals of the frame saw tooth waves, deflecting means under control of said saw tooth waves to cause the electron ray to scan lines in successive fields on said screen, means including a resistor-condenser network in series with an electron tube responsive to said frame pulses to change the interval of the first line saw tooth wave for alternate fields to cause the electron ray to scan different lines in alternate and intermediate fields on said screen, and a coupling between said second generator means and said first generator means to cause said frame pulses to control the last line saw tooth wave for each scanned field for interlocking line and frame scanning actions.

2. In a television system, a receiver to receive picture signals, line synchronizing pulses and individual frame synchronizing pulses occurring between groups of line pulses, means under control of said synchronizing pulses to produce line saw tooth waves, means under control of said frame pulses to produce frame saw tooth waves, a cathode ray viewing tube having an image screen and an electron ray directed toward the screen, line deflecting means including an amplifier responsive to said line saw tooth waves to cause horizontal forward and backward deflection of the electron ray across said screen, frame deflecting means responsive to said frame saw tooth waves to cause the electron ray to scan successive fields on said screen to produce thereon pictures from said picture signals, and means including an automatic regulating device coupled to said amplifier and responsive to said line saw tooth waves to control the horizontal forward speed of the electron ray.

3. In a television system, a receiver to receive a carrier wave modulated with picture signals, line synchronizing pulses and individual frame synchronizing pulses, occurring between groups of line pulses, each of the frame pulses of relatively long duration as compared to the duration of any one of the said line pulses, frame pulse selecting means comprising an electron tube having a resistor-condenser network for selecting the frame pulses from said received synchronizing pulses, said network being of such value as to render said tube conductive only to pulses of long duration to select and amplify each of the said frame pulses, line generator means under control of said synchronizing pulses to produce line saw tooth waves, means under control of said amplified frame pulses to produce frame saw tooth waves, a cathode ray viewing tube having an image screen and an electron ray directed toward the screen, line deflecting means including an amplifier responsive to said line saw tooth waves to cause horizontal forward and backward deflection of the electron ray across said screen, frame deflecting means responsive to said frame saw tooth waves to cause the electron ray to scan successive field on said screen to produce thereon pictures from said picture signals, and means including an automatic regulating device coupled to said amplifier and responsive to said line saw tooth waves to control the horizontal forward speed of the electron ray.

4. In a television system, a receiver to receive picture signals, line synchronizing pulses and in-= dividual frame synchronizing pulses occurring between groups of line pulses, means under control of said synchronizing pulses to produce line saw tooth waves, means under control of said frame pulses to produce frame saw tooth waves, a cathode ray viewing tube having an image screen and an electron ray directed toward the screen,*1ine deflecting means responsive to said line saw tooth waves to cause horizontal deflection of the electron ray across said screen, frame deflecting means including an amplifier responsive to said frame saw tooth waves to cause vertical forward and backward deflection of the electron ray to scan successive fields on said screen to produce thereon pictures from said picture signals, and means including an automatic regulating device coupled to said amplifier and responsive to said frame saw tooth waves to control thevertical forward speed of the electron ray.

5. In a television system, first generator means to produceline saw tooth waves, second generatormeans to produce frame saw tooth waves, a cathode ray tube having an image screen and an electron ray directed toward the screen, means including a first electron tube under control of said line saw tooth waves to select a first recurring period of time and a second recurring period in the intervals of increasing ampltiude in said line saw tooth waves, deflecting means under control of said line and frame saw tooth waves to cause the electron ray to scan successive frames on said screen during said first recurring period to produce picture signals representative of a scene within the View of said cathode ray tube,

means including a first gate amplifier under control of said first electron tube to transmit said picture signals during said first recurring period, means including a second gate amplifier under control of said first tube to transmit signals, representative of a message to accompany said picture signals, during said second recurring period, and means including a coupling between said first tube and said cathode ray tube to substantially extinguish the electron ray during said second recurring period.

6. In a television system, first generator means to produce line saw tooth waves, second generator means to produce frame saw tooth waves, a cathode ray tube ha ing an image screen and an electron ray directed toward the screen, means including a plurality of electron tubes under control of said line saw tooth Waves to select a first recurring period of time, a second recurring period and a third recurring period in the intervals of increasing amplitude in said line saw tooth waves, deflecting means under control of said line and frame saw tooth waves to cause the electron ray to scan successive fields on said screen during said first recurring period to produce picture signals representative of a scene within the View of said cathode ray tube, means including a first gate amplifier under control of a first one of said electron tubes to transmit said picture sig nals during said first recurring period, means including a second gate amplifier under control of said first electron tube to transmit signals, representative of a message to accompany said picture signals, during said second recurring period,

means including a third gate amplifier under 7. In a television system, a cathode ray'tube having an image screen and an electron ray directed toward the screen, first generator means to produce line saw tooth waves, second generator means to produce frame saw tooth waves,

means including a first electron tube and a second electron tube responsive to said line saw tooth waves to select a first recurring period of time, a second recurring period and a third recurring period in the intervals of increasing amplitude in said line saw tooth waves, deflecting means under control of said line and frame saw tooth waves to cause the electron ray to scan said screen in two directions during said first recurring period to produce picture signals representative ofa scene within the view of said cathode ray tube, means including a first gate amplifier un-' der control of said first electron tube to transmit said picture signals during said first recurring period, means including a second gate amplifier under control of said first electron tube to transmit signals, representative of a message to accompany said picture signals, during said second recurring period, and means including a third gate amplifier under control of said second electron tube to transmit signals representative of another message. 7

8. In a television system, a receiver to receive picture signals, spaced line synchronizing pulses and groups of frame synchronizing pulses occurring between groups of line pulses, each of the,

said frame pulses of relatively long duration as compared to the duration of any one of the said line pulses, frame pulse selecting means comprising a first resistor-condenser network of such value to select groups of long duration pulses from said received line and frame synchronizing pulses and an electron tube having a second resistor-condenser input network, said second network being of such value as to render said tube conductive only to the last pulse in each group of said selected frame pulses to produce single spaced frame pulses for the groups of said received frame pulses, line generator means under control of said line pulses and said single frame pulses to produce line saw tooth waves, frame generator means under control of said single frame pulses to produce frame saw tooth waves, a cathode ray tube having an image screen and an electron ray directed toward the screen, and deflecting means under control of said saw tooth waves to cause the electron ray to scan successive fields on said screen to produce thereon pictures from said picture signals.

9. In a television system, a cathode ray camera tube having an image screen and an electron ray directed toward the screen, generator means to produce first line saw tooth waves including line synchronizing pulses to control the duration of the line saw tooth waves, generator means to produce first frame saw tooth waves including frame synchronizing pulses to control the duration of the frame saw tooth waves, means including a first electron tube under control of said 7 line saw tooth waves to select a first recurring period of time and a second recurring period in the intervals of increasing amplitude in said line saw tooth waves, deflecting means under control of said line and frame saw tooth waves to cause the electron ray to scan successive frames on said screen during said first recurring period to produce picture signals representative of a scene within the view of said camera tube, means to produce a carrier wave, a modulation amplifier, means including a first signal amplifier under control of said first electron tube for supplying said picture signals to said modulation amplifier during said first recurring period to transmit over said carrier wave, means including a second sigi7 iial amplifier under control of said first electron tube for supplying messagesignals, representae tlve of a messageto accompany said picture signals, to said modulation amplifier during said second recurring period to transmit over said carrier wave, means including said modulation amplifier to transmit said synchronizing pulses over said carrier wave, a receiver to receive said picture signals, said message signals and said synchronizing pulses, a cathode ray viewing tube having a picture screen and an electron ray directed toward the screen, means under control of" said received synchronizing pulses to produce second line saw tooth waves, means under control of certain of said received synchronizing pulses to produce second frame saw tooth waves, means associated. with said receiver including a. second.

electron tube under control of said second line f. saw tooth Waves to select a first recurrent period" and a second recurrent period corresponding to said first and second recurring periods, means ineluding a first gate amplifier under control of said second electron tube to apply said received picture signals to said viewing tube during said first recurrent period, deflecting means under control of said second line and second frame saw tooth waves to cause the electron ray in the viewing tube to scan successive fields on said picture screen to produce pictures thereon from said received picture signals, a loud speaker, means including a second gate amplifier under control of said second electron tube to apply said received message signals to said speaker during said second recurrent period for producing a message.

10. In a television system, a receiver to receive a carrier wave modulated in successive rotation with picture signals representative of a scene being televised and signals representative of a message accompanying said picture signals, a cathode ray viewing tube having an image screen and an electron ray directed toward the screen, first generator means to produce line saw tooth waves, second generator means to produce frame saw tooth waves, means including a first electron tube under control of said line saw tooth waves to select a first recurring period of time and a, second recurring period in the intervals of increasing amplitude in said line saw tooth waves, means including a first gate amplifier under control of said first electron tube to apply said picture signals to said cathode ray viewing tube during said first recurring period, deflecting means under control of said line and frame saw tooth waves to cause the electron ray to scan successive fields on said screen durin said first recurring periods to produce pictures thereon from said picture signals, a signal reproducing device, means including a second gate amplifier under control of said first electron tube to apply said message signals to said device during said second recurring period for producing an audible message, and means including a coupling between said first electron tube and said viewing tube to substantially extinguish the electron ray during said second recurring period.

11. In a television system, a receiver to receive a carrier wave modulated in successive rotation with picture signals representative of a scene being televised, signals representative of a message accompanying said picture signals and synchronizing signals, a cathode ray tube having an image screen and an electron ray directed toward the screen, first generator means under control of said synchronizing signals to of. saidfirstielectrcn' tube to apply said picture signals fto' saidviewing tube during said first recurring'p'eriod, deflecting means under control of. saidiline and frame saw tooth waves to cause the 5 electron'ray to scansucce'ssive fields on saidscreenfduringi said first period to produce pic tu res thereonffrom' said'picture signals,,a signal reproducing, .device; means including a second amplifier under control of said first electron tube? to apply said message. signals to said device during saidjsecond' recurring period for produc ing an'audible message;

12; In aptelevision' system, a receiver to receive in, successive rotation picture signals resiresenta'tive 'of' a scene being televised, firstmessage signals representative of a message and second message signals representative of another message, a cathode ray tube having an image screen and an electron ray directed toward the screen, first generator means to produce line saw tooth waves, second generator means to produce frame saw tooth waves, means including at least a first electron tube and a second electron tube under control of said line saw tooth waves to select a first recurring period of time, a second recurring period and a third recurring period in the intervals of increasing amplitude in said saw tooth waves, means including a first gate amplifier under control of said first electron tube to apply said picture signals to said viewing tube during said first recurring period, deflecting means under control of said line and frame saw tooth waves to cause the electron ray to scan successive fields on said screen during said first period to pro-' duce pictures thereon from said picture signals, a signal reproducing device, a key, means including a second gate amplifier under control of said first electron tube to apply said first message signals through said key to said device during said second recurring period for reproducing an audible message, and means including a third gate amplifier under control of said second electron tube to apply said second message signals to said key.

JOHN H. HOMRIGHOUS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS (Other references, on following page) 

